pugs>sub fib (Int $n) { return 1 if $n < 2; state @seen[$n] //= fib($n-1) + fib($n-2); }
Internal error while running expression:
***
    unexpected "["
    expecting word character, "::", "=", ":=", "::=", ";" or "}"
    at <interactive> line 1, column 52

##</code><code>##

pugs>  sub fib (Int $n) { state @seen; return 1 if $n < 2; @seen[$n] //= fib($n-1) + fib($n-2); };
undef
pugs> say fib 4;
5
undef
pugs> say fib 8;
34
undef
pugs> say fib 800;
112102381301657019753922131204008107032943249802439891737991109609642417687024271467241971909001000928433174016012202680530522970872221529003044406006693244742562963426
undef